Ethylene amines are used, inter alia, as solvents, stabilizers, for the synthesis of chelating agents, synthetic resins, drugs, inhibitors and surface-active substances.
Diethylenetriamine (bis(2-aminoethyl)amine; DETA), in particular, is used as solvent for dyes and is a starting material for the production of ion exchangers, pesticides, antioxidants, corrosion inhibitors, complexing agents, textile assistants and absorbents for (acidic) gases.
Numerous processes for preparing ethylene amines, including, in particular, DETA, have been described in the literature.
According to PEP Report No. 138, “Alkyl Amines”, SRI International, March 1981, in particular pages 7, 8, 13-16, 43-107, 113, 117, the reaction of dichloroethane with ammonia at a molar ratio of 1:15 gives diethylenetriamine (DETA) in a proportion of greater than 20% by weight based on the ethylene amines formed. However, 40% by weight of higher ethylene amines are formed in addition to 40% by weight of ethylenediamine (EDA).
The formation of these higher ethylene amines (i.e. ethylene amines having a boiling point above that of triethylenetetramine (TETA)) can be substantially suppressed in favor of ethylene diamine by amination of monoethanolamine (MEOA) with ammonia (cf., for example, the abovementioned PEP Report, U.S. Pat. No. 4,014,933 (BASF AG)). However, aminoethylethanolamine (AEEA) and piperazine (PIP) are formed as by-products in this reaction.
Ind. Eng. Chem. Prod. Res. Dev. 1981, 20, pages 399-407, (C. M. Barnes et al.) describes the ammonolysis of MEOA to EDA over nickel catalysts on a mixed SiO2—Al2O3 support. Addition of water and the powdered catalyst is said to be advantageous in increasing the yield of EDA.
The conversion of EDA into DETA over transition metal catalysts is known from, for example, GB-A-1,508,460 (BASF AG) and U.S. Pat. No. 4,568,746 (UCC).
According to U.S. Pat. No. 4,568,746, the following DETA/piperazine ratios are achieved over Ni/Re catalysts: DETA/PIP=5.4-8.9 at a conversion of 33-23% at temperatures of greater than 170° C.
According to GB 1,508,460, the following ratios are achieved over Ni/Co/Cu catalysts in a fixed bed: DETA/PIP=17-26 at a conversion of 23% at temperatures of less than 150° C. and preferred pressures of 25-45 bar. No information is given on the dimensions of the catalysts.
U.S. Pat. No. 5,410,086 (Burgess) relates to the control of the DETA/piperazine ratio by adjustment of the hydrogen concentration in the liquid phase.
WO-A1-03/010125 (Akzo Nobel) describes the preparation of ethylene amines from EDA by transamination at 135-180° C., 5-40 MPa, in the presence of H2 and a specific catalyst which comprises large amounts of nickel, e.g. 26-65% by weight of Ni, on an oxidic porous support and has, for example, particle sizes of from 0.1-10 mm in a fixed or moving bed.
Disadvantages of these technologies involving suspension catalysis result, inter alia, from the need to separate the catalyst from the product. In addition, the selectivities, e.g. for the formation of DETA, are in need of improvement.
WO-A-05/061430 (BASF AG) relates to a process for increasing the space-time yield (STY) in a process for preparing a symmetrical secondary amine (e.g. DETA) by reaction of a primary amine (e.g. EDA) in the presence of hydrogen and a catalyst at a temperature in the range from 50 to 250° C. and an absolute pressure in the range from 5 to 350 bar by lowering the absolute pressure while maintaining the temperature.
WO-A-05/012223 (BASF AG) relates to a process for preparing ethylene amines (e.g. DETA) by continuous reaction of ethylenediamine (EDA) in the presence of a heterogeneous catalyst, with the reaction being carried out in a reaction column.
WO-A-05/014523 (BASF AG) relates to a process for preparing ethylene amines (e.g. DETA) by reaction of monoethanolamine (MEOA) with ammonia in the presence of a catalyst in a reactor (1) and fractionation of the resulting reaction product mixture, with ethylenediamine (EDA) obtained in the fractionation being reacted in a separate reactor (2) in the presence of a catalyst to form diethylenetriamine (DETA) and the resulting reaction product mixture being fed to the fractionation of the reaction product mixture resulting from reactor 1.
The earlier German patent application No. 102005019373.0 of Apr. 26, 2005 (BASF AG) relates to a process for preparing ethylene amines in which ethylene oxide is reacted continuously with ammonia under water-free conditions over an inorganic ion exchanger in a first reaction step to give a reaction product comprising monoethanolamine, diethanolamine and triethanolamine in a particular weight ratio and the reaction product is subsequently reacted continuously with ammonia in the presence of hydrogen and a hydrogenation catalyst in a second reaction step.
A parallel German patent application filed on the same date (BASF AG) relates to a process for preparing ethylene amines by reacting monoethanolamine (MEOA) with ammonia in the presence of specific shaped heterogeneous catalyst bodies.
A parallel German patent application filed on the same date (BASF AG) relates to a process for preparing aminodiglycol (ADG) and morpholine by reacting diethylene glycol (DEG) with ammonia in the presence of specific shaped heterogeneous catalyst bodies.